void loop() {
    WiFiClient client = server.available(); // Listen for incoming clients

    if (client)
    {
        String currentLine = "";
        while (client.connected())
        { // loop while the client's connected
            if (client.available())
            {                           // if there's bytes to read from the client,
                char c = client.read(); // read a byte, then
                        // print it out the serial monitor
                header += c;
                if (c == '\n')
                { // if the byte is a newline character
                    // if the current line is blank, you got two newline characters in a row.
                    // that's the end of the client HTTP request, so send a response:
                    if (currentLine.length() == 0)
                    {
                        if(header.indexOf("/api/") >= 0) {
                            //TODO
                            client.println("HTTP/1.1 404 Not Found");
                            client.println("Connection: close");
                            client.println();
                            client.println("Not found");
                            client.println();
                            break;
                        } else {
                            String path = midString(header, "GET ", " HTTP");
                            if(path == "/")
                                path = "/index.htm";
                            path  ="/www" + path;
                            Serial.println(path);

                            if(!SPIFFS.exists(path)) {
                                client.println("HTTP/1.1 404 Not Found");
                                client.println("Connection: close");
                                client.println();
                                client.println("Not found");
                                client.println();
                                break;
                            }

                            File f = SPIFFS.open(path, "r");

                            // HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
                            // and a content-type so the client knows what's coming, then a blank line:
                            client.println("HTTP/1.1 200 OK");
                            client.println("Content-type:text/html");
                            client.println("Connection: close");
                            client.println("Content-length: " + f.size());
                            client.println();

                            client.write(f);
                            f.close();

                            client.println();
                            break;
                        }
                    }
                    else
                    { // if you got a newline, then clear currentLine
                        currentLine = "";
                    }
                }
                else if (c != '\r')
                {                     // if you got anything else but a carriage return character,
                    currentLine += c; // add it to the end of the currentLine
                }
            }
        }
        // Clear the header variable
        header = "";
        // Close the connection
        client.stop();
    }

    //serialEvent();
    //_server.handleClient();

    //TODO: read temp sensor every 5s
    /*while(true) {
        readTempSensor();
        delay(5000);
    }*/
}